Acid resistant film forming dental composition and method of use

ABSTRACT

A method of forming a solution of oxalic acid potassium salt dihydrate, useful for desensitizing dentin, comprising the steps of admixing an effective amount of oxalic acid potassium salt dihydrate in water having a pH of 2.0-4.0, heating the solution at a temperature range from 85° F. to 100° F. until a suspension is formed, ultrasonically vibrating this suspension for an effective amount of time and frequency to reduce the oxalic acid potassium salt dihydrate to a particle size of 1 to 10 microns.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Individuals often report an immediate increase in dentin postoperativehypersensitivity or pain to sudden extremes of thermal stimuli to eithera particular tooth or a group of teeth. This may occur following eitherthe replacement of a restoration due to a recurrent carious lesionsubjacent to a previously placed restoration, the initial placement ofan existing amalgam alloy or a tooth colored resin compositerestorations or following the bleaching of teeth with power (light, heator other) assisted forms of tooth whitening systems. Patients may simplybe cautioned by the dentist to be aware of an immediate increasedfeeling of pain to a rapid jet of air, cold drinks, to chewing forces ofocclusion or to other factors such as acidic foods. Stimuli, such ascold water, cool air, osmotic gradient shifts, or sweet or acidicsolutions at the cavosurface margin of a restoration have all been shownto cause an immediate increase in the dentin pain response. Dentists maysimply call this phenomenon as patient dentin pain (postoperativehypersensitivity/DPH) or simply dental discomfort. Often patients aretold by the dentist to simply wait a few days or weeks and that the painof discomfort will become less and less, and eventually that it shouldgo away.

The acute, sharp, piercing pain of dentin pain is often a fairly commoncomplaint among many patients who have recently received a amalgam alloyor resin composite restoration in vital dentin that has been treatedwith a conventional dentin liner such as a calcium hydroxide Ca(OH)2material such as Dycal(r) or Life(r). Dentin postoperativehypersensitivity generally occurs with the normal physiologicalbreakdown of the smear layer or its removal at the cavosurface margindue to oral fluids which reach an acidic pH of 2.7 to more neutral at pH6.0.

If the dentist uses any type of instrumentation, for example, rotaryinstrumentation with a drill or bur, scraping or polishing with any sortof hand instrument, will leave a layer of debris on the tooth surfacecalled a smear layer. The breakdown of the smear layer by physiologicalaction or by the dentist, opens and exposes the dentinal tubule complexto a bi-directional flow of fluids from the dental pulp (Pashley, 1981Arch. Oral. Biol. 26: 703-706). It is this increased bidirectional fluidflow which is responsible for the patients' dentin postoperativehypersensitivity to cold or rapid air flow.

Many patients experience dentin postoperative hypersensitivity when anexisting amalgam alloy or a resin composite restoration and itsunderlying CA(OH)2 base of Dycal(r) or Life(r) washes out or is removedand the dentin loses its biological seal or simply feel the pain fromdiscomfort due to premature occlusal contact or thermal or coldextremes.

The physiological mechanism for dentin pain following placement ofeither an amalgam alloy or a resin composite restoration has beenexplained as being due to the breakdown or loss of the smear layer whichthen results in an immediate increased flow of pulpal fluids though itsmicro channel complex (Pashley, et al. 1984 Arch. Oral. Biol. 29:65-68). This increase in flow may be 94% greater than the normalphysiological flow of fluids through the normal dentin substrate.

The present invention relates to the use of an acid resistant filmforming liner material that occludes the dentinal tubules to decreasedentinal sensitivity, acid penetration and discomfort.

2. Summary of the Related Art

The aforementioned Pashley et al., articles disclose the hydrodynamictheory of flow and displacement of the contents of dental tubules undervarious conditions. Pain stimuli is transmitted to nerve structure byhydrodynamic movement of force in the tubules within the dentin. Priorart methods of alleviating pain during dental restoration proceduresinclude preparing a cavity in a tooth to receive restorative materialwith a cavity liner or cavity varnish. The material allegedly decreasesthe permeability of the dentin to other materials placed in the cavityduring this restoration in addition to blocking the attack of anymicroleakage, that is, contaminants from the oral fluids that mayattempt to penetrate the cavity in the event that the restorativematerial permits microleakage around its margins with the tooth. Priorart cavity varnishes frequently contain organic gums dissolved inorganic solvents. The organic solvent evaporates leaving a film of theorganic gum on the dentin.

These cavity lining agents are composed primarily of water and solubleorganic materials which is often placed on a liquid layer that coversthe surface of the dentin without any bonding. This may weaken anyadherence of the cavity varnish to the tooth surface and may causeleaking.

A natural cavity liner is microcrystalline debris which is found in thesurface of dentin which is cut and is referred to as a smear layer. Thesmear layer occludes the orifices of the dentinal tubules to the pointwhere bacteria cannot access the tubules. However, the smear layer isoften destroyed due to the acidity in the oral cavity and the presenceof microleakage around the filling material which is in contact with acavity varnish.

The prior art also includes the use of oxalate salts to desensitizehypersensitive dentin or cementum surfaces on teeth, for example, asdisclosed in U.S. Pat. No. 4,057,621. U.S. Pat. No. 4,538,990 disclosesa two-step method using different oxalate acids salts to decrease thepermeability of a dental cavity prepared for receiving a restorativematerial. The method involves sequential application of the oxalatesalts to the smear layer. First, a 1 to 30% weight to volume neutraloxalate salt solution, for example, dipotassium oxide, is applied andthen followed within one or two minutes by an application of 0.5 to 3%weight to volume percent of an acidic oxalate solution, such asmonopotassium mono hydrogen oxalate. The neutral oxalate forms largecalcium oxalate crystals over the dentin surface and the acid oxalateforms smaller crystals around the previously precipitated largercrystals to form a uniform layer of crystals.

U.S. Pat. No. 2,746,905 discloses the use of dehydroacetic acid and thesoluble salts to maintain the pH of the mouth to about 5.2 to preventthe dissolution of inorganic tooth enamel material which includes theuse of oxalate in the composition as an enamel protective agent toincrease the resistance of the tooth to acid attack.

In contrast to the above literature and patents, the present inventionutilizes a specific oxalic acid salt, oxalate acid potassium salt,dihydrate, 99% which when applied to the surface of the tooth penetratesinto the tubules and fibriles of the dentin layer. The oxalic acidpotassium salt dihydrate, or it may be simply referred to as potassiumoxalate dihydrate, eliminates fluid movement within the tubules andtherefore limits the dentin to be incapable of transmitting painfulstimuli to the pulp in the form of fluid movement Therefore, no pain ordiscomfort is felt by the patient for long periods of time.

SUMMARY OF THE INVENTION

The present invention relates to a method of utilizing a solution ofoxalic acid potassium salt, dihydrate, 99% as referred to hereinafter aspotassium oxalate dihydrate, to react with ionized calcium in thedentinal fluid forming an insoluble white precipitate of calcium oxalatethat includes the dentinal tubules. This action leads to decreasedpermeability of dentin, decreased acid penetration of dentin anddecreased dentinal sensitivity. The solution of potassium oxalatedihydrate contains about 1.5 to about 10% by weight oxalic acidpotassium salt dihydrate and has a pH ranging from about 2.0 to about4.0.

It is an object of the present invention to provide a method of using asolution of oxalic acid potassium salt dihydrate to decreasepermeability of dentin.

Another object of the present invention is to provide a method of usinga solution of oxalic acid potassium salt dihydrate to decrease dentinsensitivity.

Another object of the present invention is to provide a method of usinga solution of oxalic acid potassium salt dihydrate to decrease acidpenetration of dentin.

And, yet another object of the present invention is to provide a simplediagnostic test to determine if dental pain or discomfort is reversibleor irreversible.

Another object of the present invention is to provide a method tosolubilize oxalic acid potassium salt dihydrate in water so that it isavailable in a dosage form to serve as a desensitizing agent.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a table showing the results of the clinical evaluationdescribed in Example 3. The product of the present invention isdescribed as Super Seal.

DETAILED DESCRIPTION OF THE INVENTION

The mechanism action of the potassium oxalate as well as itseffectiveness in reducing dental sensitivity had been reported byPashley, et al. in the literature, see Pashley, D. H. et. al. (1983):Dentin Permeability—Effects of Desensitizing Dentrifices In Vitro, J.Periodontol. 55: 522-525; Pashley, D. H. and Galloway (1985): TheEffects of Oxalate Treatment on the Smear Layer of Ground Surfaces ofHuman Dentine. Arch Oral. Biol. 30: 731-737; Pashley, D. H. (1989):Dentin: A Dynamic Substrate—A Review. Scanning Micros 3: 161-176;Pashley, E. L. et al. (1989) Dentin Permeability and Bond Strengthsafter Various Surface Treatments. Dent. Mater 5: 375-378.

Pashley, et. al. discloses a potassium oxalate form of protective layerof insoluble calcium oxalate on the surface of the exposed dentin thatoccludes open tubules. The occlusion causes a decrease inhydroconductance and tubule permeability as well as a decrease in acidpenetration and, ultimately a reduction in dentinal sensitivity. U.S.Pat. No. 4,057,621 discloses potassium oxalate compounds useful in theinvention comprising a method of desensitizing hypersensitive dentin andcementum. In the method, a member selected from the group consisting ofa mono and di-substituted alkali metal and ammonium oxalate in anaqueous solution is applied in an effective amount to the dentin andcementum to desensitize the area. Compounds disclosed in the patentinclude the following, which are shown with their water solubility. Theyare described in the 54th and 76th Editions, Handbook of Chemistry andPhysics (1973-74 and 1995-96).

Dipotassium oxalate (K₂C₂O₄.H₂O) 33.0 Hot Water Solubility Potassiumhydrogen oxalate (KHC₂O₄) 16.7 Hot Water Solubility Sodium oxalate(Na₂C₂O₄) 6.33 Hot Water Solubility Sodium hydrogen oxalate(NaHC₂O₄.H₂O) 21.0 Hot Water Solubility Lithium oxalate (Li₂C₂O₄)  8.0Cold Water Solubility Lithium hydrogen oxalate (LiHC₂O₄.R₂O) No readingAmmonium oxalate [(NH₄)₂C₂O₄.H₂O] 11.8 Hot Water Solubility Hydrogenoxalate (NH₄HC₂O₄.H₂O) No reading

The active ingredient in the present invention is oxalate acid potassiumsalt, dihydrate 99% with a molecular weight of 254.19 and a formula ofC₄H₃KO_(8.2)H₂O. The oxalate potassium salt, dihydrate 99% or referredto herein as potassium oxalate dihydrate is a white crystaline powderthat is slightly soluble in water, having a solubility of 29 Gm/ liter.The potassium oxalate dihydrate is utilized preferably in an aqueoussolution. Dissolving the potassium oxalate dihydrate in water may bedifficult under conventional practices, however, the product of thepresent invention is subjected to ultrasonic frequencies to disperse thelarge crystals of the potassium oxalate in water and thereforesolubilize in water. This treatment renders the potassium dihydrate intoa particle size which is adequate and sufficient for the purposes ofthis invention. Any treatment to solubilize the potassium oxalatedihydrate in water will be satisfactory, however, the use of variablehigh frequency sound waves is preferred.

In order to prepare the product of the present invention, doubledistilled deionized water, with a water purity of 1,000,000 to 5,000,000resistance in ohms, according to standardized testing of the AmericanNational Standards Institute. The high resistance equates to highpurity. Other forms of purified water may be utilized, however, thedouble distilled deionized water is preferred. Sufficient oxalic acidpotassium salt, dihydrate 99% crystals are added to the water so thatthe amount in the final solution ranges from 1.5% to 4.0% weight tovolume. Preferably, the amount is about 2.9% by weight in the finalproduct. The water and crystals are then subjected to variable ultrahigh frequency wave action to disintegrate the crystals into very smallparticles to form a solution. This is typically accomplished by using anultrasonic cell disrupter, however, any means can be used to solubilizethe oxalic acid potassium salt, dihydrate. Preferably, an ultrasoniccell disruptor such as identified as the Branson Sonifier or equivalentcan be utilized. The sonifier converts electrical energy from a powersupply to mechanical vibration. In this apparatus, the water andpotassium oxalate dihydrate crystals are placed in a mixing containerand attached to a pumping system. The pump is started to circulate thewater in a continuous flow at about ½ liter per minute. The water andcrystals are circulated in the chamber for about 30 minutes. Thisprocess uses a variable ultra high frequency wave focused in a smallchamber directly on the crystals in the water. The mechanical vibrationmay range to 20,000Hz. In use, the preferred vibrations provide ultrasonic disassociation at a frequency of about 16,000 Hz to about 20,000Hz at the tip of the ultrasonic horn as it disrupts and disintegratesthe crystals into very small particles to so that they go into solution.The water and crystal mixture passes the ultrasonic horn multiple timeswhich continues to disintegrate the crystals into smaller particles eachtime it passes. Preferably, the particle size in the final product ofone liter approximates about 1 to 4 microns when viewed under a 100power microscope. About 60% of the particles are of this size. Theremainer of the particles may range from about 5 to about 10 microns.After solublization, no precipate is visible after 24 hours with theunaided human eye. Larger particles sizes are acceptable, however,particle sizes in the range of about 1 microns to 10 microns arepreferred, and most preferably the particle size is about 1 to 4microns.

The acidic solution has a pH ranging from about 2.0 to 4.0 with thepreferred range being about 2.7 to about 3.0. Most preferably, the pH is3.0. The pH of the acidic solution is controlled by the amount ofpotassium oxalate dihydrate that is used in the formulation. The largerthe amount of the potassium oxalate dihydrate the lower the pH.

In operation, the use of potassium oxalate dihydrate is a one stepprocess to stop sensitivity to cold and air immediately. It is alsohelpful as a diagnostic aid to assist the dentist in differentiatingbetween reversible fluid flow in dentin and nonpulp inflammation andirreversible fluid flow which is results in pulp inflammation. About 3-6drops of potassium oxalate dihydrate can be placed in a clean Dappendish using forceps so that a small, sterile cotton pallet can besaturated with the potassium oxalate dihydrate which is then gentlyrubbed or dabbed onto the affected tooth area for at least thirtyseconds. The solution may be gently rubbed around the margin or over thecrown cementum or exposed root surfaces as well as onto the exposed rootof teeth which are sensitive to cold or air stimuli. Brushing theproduct on the tooth surface is not necessary and should not beaccomplished. No rinsing is needed. After application, a gentle airdispersion may be applied to the surface to evaporate the solution fromthe area leaving a frosty white surface which is an acid resistantmineral layer that stops fluid movement or dentin hypersensitivity tocold and air stimuli. It is not necessary to blast air on the toothsurface because it could remove the solution.

The product of the present invention can be applied on prepared toothstructure such vital dentin both before and after oral hygiene treatmentfor prophylaxis for cleaning and scaling. The product may be used as aone-step replacement under all crowns and inlays with veneerpreparation. It can be used on the dentin of all cavity preparation foramalgam alloys, and resin composite restoration. The acid resistant filmforming liner material can have bonding materials applied directly onits surface for binding restorative materials. It may also be applied onthe tooth surface following a bleaching procedure whether the procedureis done in a dentist's office or if the patient uses a home bleachingkit. In addition, the potassium oxalate dihydrate solution can be usedas a diagnostic tool to differentiate between acute dentinal pain andchronic pulpal pain. Acute dentin pain is generally called a reversibletooth pain. To the dentist and patient, this means that there is adefect located within the substance of the dentin and not within thenerves within the dental pulp. The problem is reversible without anyinvasive endodontic treatment. Alternatively, chronic dental pain is anirreversible stimulus which indicates that the nerves of the dentalpulpal are inflamed and must be removed by some sort of biomechanicalendodontic instrumentation. The potassium oxalate dihydrate of thepresent invention provides a simple one-step diagnostic treatment thatallows the dentist to discriminate reversible and irreversible dentalpain. When a patient complains of pain to cold and air and there are nodiagnostic features of radiographic presence of a periapicalradiolucency, fractured tooth root or other obvious clinical problemsthen the dentist may simply rub the potassium oxalate dihydrate of thepresent invention onto and around edges or cavosurface margins of thetooth restoration interface. If the patient reports an immediatecessation to dental pain then the dentist may complete the diagnosisthat the problem is fluid flow in the dentin or microleakage. This isconfirmation of reversible pulp inflammation and may be treated by therepair of the restoration and not the removal of the pulp.

In order to explain the mechanism of action of the present invention,the following is a description of the mode of action of the presentinvention used in, for example, a restorative procedure. However, themode of action is similar for all applications. Acidic solution ofpotassium oxalate dihyrate of the present invention initially serves tobreak down the smear layer and opens the substrate of dentin, as well asenamel and cementum. Buffering occurs to the pH of the potassium oxalatedihydrate and as the reaction progresses, the pH of the solution themoves toward neutrality. Simultaneously, the calcium granular particlesprecipitate on the entire cavity surface in addition to any smallphysiological cracks which are normally present in adult enamel and orcementum of the root surface. This granular precipitate, when dried, isan acid resistant lining layer that is chemically bound to the surfaceas well as into the dentinal tubules of the cavity. Once the granularcrystals are formed, the barrier effect is immediately felt by thepatient. To the unaided eye, there is a slightly whitish film that maybe seen on the surface of the cavity and tooth.

EXAMPLE 1 Preparation of Solution

Twenty-nine (29) grams of oxalate potassium salt, dihydrate 99%, a whitecrystalline substance, were added to one liter of double distilleddeionized water in a mixing container. The container is capped andaffixed to a Branson Sonifer manufactured by Branson UltrasonicCorporation of Danbury, Conn. The feed and return hoses were connectedbetween the container and sonifer. The pump on the sonifer was startedto recirculate the water at a setting of ½ liter per minute. The soniferwas started at a setting of constant duty cycle, time on hold, outputcontrol at .9 or 18,000 Hz.

The water was subjected to ultrasonic disassociation or vibrations for30 minutes. The water was allowed to set for 30 minutes and samples weretaken for viewing under a 100× power microscope. The size of thecrystals was about 10 microns.

EXAMPLE 2 Preparation of Solution With Heated Water

One liter of double distilled water was heated and mixed with a stir barin a vessel until the temperature reaches 850° F. to 100° F. A hot platewas utilized for heating the water. Twenty-nine (29) grams of oxalatepotassium salt, dihydrate 99% was added to the vessel and mixed with thestir bar so that the white opaque oxalate potassium salt dihydrate 99%becomes clear or relatively transparent to the unaided eye. When thesolution became relatively transparent, the potassium salt was insuspension. The solution was then added to the sonifer as described inExample 1 for ultrasonic disassociation of the oxalate potassium salt,dihydrate 99%. It was sonicated for about 40 minutes at 18,000 Hz toyield a clear solution.

EXAMPLE 3 Clinical Evaluation

To show the desensitization properties of the potassium oxalatedihydrate of the present invention, amalgam restoration patients weretreated with a commonly used, commercially available cavity varnish orthe product of the present invention prior to placement of an amalgam.Prior to anesthesia for pre-treatment evaluation and during the firstweek of treatment, the patients completed a questionnaire on pain. Thepatients were also evaluated post-operatively at one, three and sixweeks. The results of the study demonstrate a reduction inpost-operative hypersensitivity, especially cold, in patients treatedwith the potassium oxalate dihydrate of the present invention.

MATERIALS AND METHODS

A total of 65 human teeth with active carious lesions precluding eitheracute or chronic dentin postoperative hypersensitivity symptomatologywere selected to be restored with the commercially available amalgamalloy Tytin(r). Only patients who had elected amalgam restorationprocedures at UAB were employed for this study. Each tooth received apre anesthesia evaluation for dentin postoperative hypersensitive with acold stimulus and air jet for thermal testing. For cold-ice testing,plastic needle covers were filled with water and frozen in arefrigerator freezer for uses as the standardized cold stimulus.

For air stimulation, the standardized baseline air jet from a syringewas used to direct a blast of air at the offending tooth and defectiverestoration. A randomized number chart was employed to select teeth foreither the Copalite(r) varnish controls or teeth to be treated with theproduct of the present invention, potassium oxalate dihydrate.

Amalgam Preparations

Following pre operative data collection and anesthesia, each tooth thenreceived a routine intracoronal Class-I or Class-II cavity preparations.

All 65 teeth 35 intracoronal Copalite® controls and 30 teeth to betreated with the product of the present invention, potassium oxalatedihydrate, received Class-I or Class-H cavity preparations—prepared witheither a new #245 or #330 carbide bur at ultra high speed, under waterspray and high speed evacuation. Following cavity preparation, rinsingand gentle air drying, the entire preparation surface was treated withthe Copalite® varnish without modification or removal of the smearlayer. Each control cavity was treated with three layers of copalvarnish and each layer gently air dispersed with a chip syringe beforethe following Copalite® coat was applied. A metal matrix was placed onall Class II cavity preparations and the tooth was restored toanatomical contour with the dispersed phase spherical amalgam alloyTytin®.

All other clinical preparation procedures, testing criteria and recallswere identical to those employed with the 39 teeth treated with theproduct of the present mention. An additional 30 teeth were treated withthe product of the invention, potassium oxalate dihydrate. Followingintracoronal Class-I or Class-H cavity preparations for caries removal,the cavity was cleaned with sterile water, gently air dispersed and theprepared cavity surface treated twice with potassium oxalate dihydrate.The potassium oxalate dihydrate solution was dispensed into a cleanDappen dish and then absorbed into a sterile cotton pellet. The entiresurface area of the cavity of prepared enamel and dentin surface wasmechanically swabbed for approximately 2 minutes, air dispersed andagain treated as before. The surface was gently air dried, the matrixplaced and the cavity restored with Tytin®.

Prior to anesthesia for pretreatment evaluation and during the 1st weekof treatment, the patient was recalled to the clinic to fill out a formas to their own perception of “feeling” or response to various stimuli,including cold, hot, sweets, biting, and brushing. The patient was alsoevaluated for postoperative hypersensitivity at one, three and six weekspost-operatively. The subjective consideration of patients' data werecollected by having the patient cross the 10 cm line at a point wherethey felt their range of pain was indicated. The McGill Visual analogscale was noted at each time interval. Thermal tests for ice and an airjet were administered and data recorded as for all of the previoustests.

For base line data, each patient was evaluated for pain or sensitivityto cold and air prior to their treatment in this study. A total of 35patients were treated in the control in the Copalite® group and 30patients were treated in the potassium oxalate dihydrate group—for atotal study group of N=65.

All data was analyzed by one-way Analysis of Variance (ANOVA) at the0.05 level depending on the cell sizes in our contingency table oftreatments versus responses. Differences between the various groupswithin the ANOVA was compared using the Student T test (p<0.050).

RESULTS

Questionnaire Responses

Responses from each of the patients were recorded on separate sheets andthen tabulated onto the master sheet according to the identifiedcriteria. The raw data were recorded from the McGill Visual Analog Scale(MVAS) evaluation sheets. Data were recorded from all patients.experiencing none, some or severe post-operative hypersensitivity basedon the patient responses at the various intervals, preoperative at 0days, and post treatment 5, 7, 21 and 42 days. In each case responseswere reported to the various test stimuli; cold, hot, sweet, biting ofpercussion, and brushing and flossing. Evaluation forms were completed.

The date for each of the McGill VA scales were tabulated and recorded ona separate sheet with the patient's name and clinical record number—as a10 centimeter straight line with no identifying marks along its axis.

Approximately 12% of the patients experienced some sort of preoperativehypersensitivity, in response to questions concerning pain—mostly to thecold stimulus. However, 65% of the patients claimed some sort ofpre-operative response on the MVA scale—of which over ½ of thesepatients (52%) marked values of 0-1 mm on a scale on the 10 centimeterpre-operative scale. Only 2% of the total population experienced anypre-operative pain greater than 5mm on the 10 centimeter MVA scale.

Following routine caries excavation, application of potassium oxalatedihydrate or Copalite control solutions, and placement of the amalgamrestoration, patients showed a reduction in sensitivity postoperatively.In those individuals who had received the control Copalite(r) treatment,there was a 2.3% reduction in sensitivity to the various stimuli(especially cold), in response to direct questioning. However, among thepatients treated with the potassium oxalate dihydrate of the presentinvention, there was an overall reduction in their reported pain by alevel of 80.3%.

The collective data from the MVA scale show a dramatic reduction inpost-operative pain in those teeth which were treated withpotassiumoxalate dihydrate while only 68.7% of the Copalite(r) patientsexhibited temporary pain reduction post-operatively.

The data show that for the cold discriminator measurement there was agreater reduction in overall pain reduction with Super Seal than thecommercially available Copalite(r). Furthermore, patient responses tothe MVA survey document showed the majority of individuals experiencedno post operative pain with the product of the present invention,potassium oxalate dihydrate. Overall, 25.7% of the patients treated withCopalite(r) and 88.5% of those patients' teeth treated with potassiumoxalate dihydrate were pain free following the first procedure.

Complete test results are shown in FIG. 1. The product of the inventionis defined as Super Seal in the table.

It should be understood that the foregoing disclosure emphasizes certainspecific embodiments of the invention and that all modifications oralternatives equivalent thereto are within the spirit and scope of theinvention set forth herein.

What is claimed is:
 1. A method of forming a solution of oxalic acidpotassium salt dihydrate comprising: admixing an effective amount ofoxalic acid potassium salt dihydrate crystals in water having a pH ofabout 2.0 to 4.0, heating the solution at a temperature range from about85° F. to about 100° F. until a suspension is formed, ultrasonicallyvibrating the suspension for an effective amount of time and frequencyto reduce the oxalic acid potassium salt dihydrate crystals to aparticle size of about 1 to about 10 microns when the suspension isviewed through a 100 power microscope.
 2. The method of claim 1 whereinthe effective amount of oxalic acid potassium salt dihydrate is theamount needed to form a solution that desensitizes dentin and cementumand decreases the permeability of a prepared cavity surface in a tooth.3. The method of claim 2 wherein the amount of oxalic acid potassiumsalt dihydrate is about 1.5% to about 10% by weight in the finalproduct.
 4. The method of claim 3 wherein the amount of oxalic acidpotassium salt dihydrated is about 2.9% by weight in the final product.5. The method of claim 1 wherein the pH of the solution is about 3.0. 6.The method of claim 1 wherein the particle size of the crystals isindicated by not being visible by the naked eye about 24 hours afterformation of the solution.
 7. The method of claim 6 wherein the particlesize of the crystals is about 1 to about 4 microns.
 8. The method ofclaim 1 when the oxalic acid potassium salt dihydrate solution, in avolume of 1 liter, is heated and mixed for about 40 minutes prior toultrasonic disassociation.
 9. The method of claim 1 wherein the water ispurified.
 10. The method of claim 1 wherein the water is doubledistilled and de-ionized.
 11. The method of claim 1 wherein the solutionis vibrated in a sonifier.
 12. The method of claim 1 wherein thesonifier vibrates the solution at an energy level up to 20,000 Hz. 13.The method of claim 1 wherein the solution is vibrated at an energylevel of about 16,000 Hz to about 19000 Hz.
 14. The method of claim 13wherein the solution is vibrated at an energy level of about 18,000 HZ.15. The method of claim 12 wherein the solution is vibrated for about 30minutes.
 16. A method of decreasing the permeability of dentincomprising applying to the dentin an effective amount of the productproduced by the method of claim 1.